1.\" $OpenBSD: fstab.5,v 1.51 2014/07/13 17:39:57 jmc Exp $ 2.\" $NetBSD: fstab.5,v 1.5.2.1 1995/11/16 20:11:11 pk Exp $ 3.\" 4.\" Copyright (c) 1980, 1989, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)fstab.5 8.1 (Berkeley) 6/5/93 32.\" 33.Dd $Mdocdate: July 13 2014 $ 34.Dt FSTAB 5 35.Os 36.Sh NAME 37.Nm fstab 38.Nd static information about the filesystems 39.Sh SYNOPSIS 40.Fd #include <fstab.h> 41.Sh DESCRIPTION 42The 43.Nm 44file contains descriptive information about the various file systems. 45.Nm 46is only read by programs, and not written; 47it is the duty of the system administrator to properly create 48and maintain this file. 49Each filesystem is described on a separate line; 50fields on each line are separated by tabs or spaces. 51Lines beginning with the 52.Sq # 53character are comments and are ignored. 54The order of records in 55.Nm 56is important because 57.Xr fsck 8 58and 59.Xr mount 8 60sequentially iterate through 61.Nm 62doing their thing. 63.Pp 64A line has the following format: 65.Bd -literal -offset indent 66fs_spec fs_file fs_vfstype fs_mntops fs_freq fs_passno 67.Ed 68.Pp 69The first field, 70.Fa fs_spec , 71describes the block special device or remote filesystem to be mounted. 72A block special device may be specified by pathname 73or by 74.Xr disklabel 8 75UID (DUID). 76For filesystems of type MFS 77the special file name is typically that of the primary swap area; 78if the keyword 79.Dq swap 80is used instead of a special file name, 81default configuration parameters are used. 82If a program needs the character special file name, 83the program must create it by appending an 84.Sq r 85after the last 86.Sq / 87in the special file name. 88.Pp 89The second field, 90.Fa fs_file , 91describes the mount point for the filesystem. 92For swap partitions, this field should be specified as 93.Dq none . 94.Pp 95The third field, 96.Fa fs_vfstype , 97describes the type of the filesystem. 98The system currently supports the following types of filesystems: 99.Pp 100.Bl -tag -width indent -offset indent -compact 101.It cd9660 102An ISO 9660 CD-ROM filesystem. 103.It ext2fs 104A local Linux compatible ext2fs 105filesystem. 106.It ffs 107A local 108.Ux 109filesystem. 110.It mfs 111A local memory-based 112.Ux 113filesystem. 114.It msdos 115An 116.Tn MS-DOS 117FAT filesystem. 118.It nfs 119A Sun Microsystems compatible Network File System. 120.It ntfs 121An NTFS filesystem. 122.It procfs 123A local filesystem containing process information. 124.It swap 125A disk partition to be used for swapping. 126.It tmpfs 127A local memory-based 128.Ux 129filesystem. 130.It udf 131A UDF filesystem. 132.It vnd 133A VND image file. 134.El 135.Pp 136The fourth field, 137.Fa fs_mntops , 138describes the mount options associated with the filesystem. 139It is formatted as a comma separated list of options. 140It contains at least the type of mount (see 141.Fa fs_type 142below) plus any additional options appropriate to the filesystem type. 143.Pp 144The option 145.Dq auto 146can be used in the 147.Dq noauto 148form to cause 149a file system not to be mounted automatically (with 150.Ic mount -A 151or 152.Ic mount -a , 153or at system boot time). 154Similarly, the option 155.Dq net 156can be used to cause a file system to be considered only if the 157.Fl N 158flag is passed to 159.Xr mount 8 160or 161.Xr fsck 8 . 162.Pp 163If the options 164.Dq userquota 165and/or 166.Dq groupquota 167are specified, the filesystem is automatically processed by the 168.Xr quotacheck 8 169command, and user and/or group disk quotas are enabled with 170.Xr quotaon 8 . 171By default, filesystem quotas are maintained in files named 172.Pa quota.user 173and 174.Pa quota.group 175which are located at the root of the associated filesystem. 176These defaults may be overridden by putting an equal sign 177and an alternative absolute pathname following the quota option. 178Thus, if the user quota file for 179.Pa /tmp 180is stored in 181.Pa /var/quotas/tmp.user , 182this location can be specified as: 183.Bd -literal -offset indent 184userquota=/var/quotas/tmp.user 185.Ed 186.Pp 187The type of the mount is extracted from the first parameter of the 188.Fa fs_mntops 189field and stored separately in the 190.Fa fs_type 191field (it is not deleted from the 192.Fa fs_mntops 193field). 194If 195.Fa fs_type 196is 197.Dq rw , 198.Dq rq , 199or 200.Dq ro 201then the filesystem whose name is given in the 202.Fa fs_file 203field is normally mounted read-write or read-only on the 204specified special file. 205If 206.Fa fs_type 207is 208.Dq sw 209then the special file is made available as a piece of swap space by the 210.Xr swapon 8 211command at the end of the system reboot procedure. 212The fields other than 213.Fa fs_spec 214and 215.Fa fs_type 216are unused. 217If 218.Fa fs_type 219is specified as 220.Dq xx 221the entry is ignored. 222This is useful to show disk partitions which are currently unused. 223.Pp 224The fifth field, 225.Fa fs_freq , 226is used by the 227.Fl W 228and 229.Fl w 230options of 231.Xr dump 8 232to recommend which filesystems should be backed up. 233The value specifies the number of days 234after which a dump is regarded as being old; 235if it is not present, a value of zero is returned and 236.Xr dump 8 237will assume that the filesystem does not need to be dumped. 238.Pp 239The sixth field, 240.Fa fs_passno , 241is used by the 242.Xr fsck 8 243program to determine the order in which filesystem checks are done 244at reboot time. 245The root filesystem should be specified with a 246.Fa fs_passno 247of 1, and other filesystems should have a 248.Fa fs_passno 249of 2. 250Filesystems within a drive will be checked sequentially, 251but filesystems on different drives will be checked at the 252same time to utilize parallelism available in the hardware. 253If the sixth field is not present or is zero, 254a value of zero is returned and 255.Xr fsck 8 256will assume that the filesystem does not need to be checked. 257.Bd -literal 258#define FSTAB_RW "rw" /* read/write device */ 259#define FSTAB_RQ "rq" /* read/write with quotas */ 260#define FSTAB_RO "ro" /* read-only device */ 261#define FSTAB_SW "sw" /* swap device */ 262#define FSTAB_XX "xx" /* ignore totally */ 263 264struct fstab { 265 char *fs_spec; /* block special device name */ 266 char *fs_file; /* filesystem path prefix */ 267 char *fs_vfstype; /* type of filesystem */ 268 char *fs_mntops; /* comma separated mount options */ 269 char *fs_type; /* rw, rq, ro, sw, or xx */ 270 int fs_freq; /* dump frequency, in days */ 271 int fs_passno; /* pass number on parallel fsck */ 272}; 273.Ed 274.Pp 275The proper way to read records from 276.Pa fstab 277is to use the routines 278.Xr getfsent 3 , 279.Xr getfsspec 3 , 280and 281.Xr getfsfile 3 . 282.Sh FILES 283.Bl -tag -width /etc/fstab -compact 284.It Pa /etc/fstab 285.El 286.Sh EXAMPLES 287Here is a sample 288.Pa /etc/fstab 289file: 290.Bd -literal -offset indent 291/dev/sd0b none swap sw 292/dev/sd1b none swap sw 293/dev/sd0a / ffs rw 1 1 294/dev/sd0e /var ffs rw,nodev,nosuid 1 2 295#/dev/sd0f /tmp ffs rw,nodev,nosuid 1 2 296swap /tmp mfs rw,nodev,nosuid,-s=153600 0 0 297/dev/sd0g /usr ffs rw,nodev 1 2 298/dev/sd0h /usr/local ffs rw,nodev 1 2 299/dev/sd0i /home ffs rw,nodev,nosuid 1 2 300/dev/sd0j /usr/src ffs rw,nodev,nosuid,softdep 1 2 301/dev/cd0a /cdrom cd9660 ro,noauto 0 0 3025b27c2761a9b0b06.i /mnt/key msdos rw,noauto 0 0 303server:/export/ports /usr/ports nfs rw,nodev,nosuid,soft,intr 0 0 304.Ed 305.Sh SEE ALSO 306.Xr quota 1 , 307.Xr getfsent 3 , 308.Xr fsck 8 , 309.Xr mount 8 , 310.Xr quotacheck 8 , 311.Xr quotaon 8 312.Sh HISTORY 313The 314.Nm 315file format appeared in 316.Bx 4.0 . 317